Submarine target simulator



2 Sheets-Sheet 1 April 14, 1970 McGANN ETAL SUBMARINE TARGET SIMULATOR Filed 001;. 16, 1968 INVENTORS ELTON X McCvAN/V ROBERT E. SHOOT Q: LL

BY JM 0 Lama} ATTORNEY April 14, 1970 g y Mcq fl ETAL 3,506,086

SUBMARINE TARGET SIMULATOR Filed Oct. 16, 1968 2 Sheets-Sheet 2 i zs l I 25 I JUL I FIG. 2

United States Patent U.S. Cl. 181-.5 7 Claims ABSTRACT OF THE DISCLOSURE A container capable of being air or hand launched into a water environment to introduce gas bubble producing pellets at varying water depths including a bomb-shaped aluminum charge holder or casing provided with a nose cap and tail fins. A plurality of large pellets of waterreactive, gas-forming material, such as lithium hydride, are contained within the charge holder between the nOse cap and an elastomeric piston adjacent the tail fins. A spring loaded valve is mounted in the tail of the charge holder and set to admit water at a predetermined depth to contact small pellets of the same chemical material carried by the piston. The gas generated by reaction between the water and the small pellets forces the valve closed and presses the piston against the large pellets. This action ejects the nose cap and deploys the large pellets to cause generation of a bubble stream simulating a submarine target.

STATEMENT OF GOVERNMENT INTEREST The invention defined herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to underwater deploying devices and more particularly to devices for deploying water reactive chemicals at predetermined depths for generating bubble streams to simulate submarine targets.

In the training of sonar operators, it has been found extremely difficult to electronically simulate actual operating conditions. The difficulties have included, inter alia, the problems of reproducing the background noise of the sea itself as well as the return signals which would be caused by various natural phenomena. A shipboard environment provides the best conditions, by far, for providing realistic and eifective training for fledgling sonar operators. To maintain the realism, it is necessary to provide targets from which sonar returns may be obtained. It is possible, of course, to station an actual submarine in the area in which the training ship is operating to provide the ultimate in realism. However, the cost is prohibitive even when the training ship has multiple equipment which permits simultaneous training for a number of men. The desideratum, then, is a means for accurately simulating the presence of a submarine at predetermined underwater locations.

It has long been known that underwater bubble formations of substantial size produce sonar returns or echoes which closely resemble those from submarines. During World War II, for example, submarine commanders would sometimes eject a quantity of compressed air from a torpedo tube in an attempt to deceive enemy sonar operators. Also, some German submarines were equipped with what was called a pillen-werfer (literally, pills thrower) which ejected pills or pellets of a water reactive chemical to cause generation of a bubble stream for decoying purposes and some American submarines were similarly equipped. This decoying technique has obvious possibilities for training sonar operators if the presence 3,506,086 Patented Apr. 14, 1970 of the submarine could be dispensed with since the cost would otherwise be prohibitive.

SUMMARY OF THE INVENTION To this end, the present invention provides a device which may be air or hand launched into the sea and which will deploy pellets of lithium hydride, or other water-reactive, gas-generating material at predetermined depths to simulate submarine targets. This enables effective training of sonar operators without the expense of providing an actual submarine as the target. The use of the same chemical compound to activate the ejection mechanism and generate the bubble stream precludes the masking of the etfects of the gas generating pellets by the ejection mechanism.

OBJECTS OF THE INVENTION It is a primary object of this invention to provide an inexpensive device which will simulate submarine targets.

It is another object of this invention to provide a device which will generate an underwater bubble stream at a predetermined depth to simulate a submarine target.

It is further object of this invention to provide a device which will deploy pellets of a water-reactive chemical underwater at predetermined depths.

It is still another object of this invention to provide a device for deploying articles underwater which may be launched from aircraft, small boats, or ships.

It is a still further object of this invention to provide an underwater article-deploying device which depends solely upon water pressure and the action of water-reactive chemicals for operation.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, advantages and novel features of the invention will become readily apparent upon consideration of the following detailed description when read in conjunction with the accompanying drawings wherein like numerals of reference designate like parts throughout the several views and wherein:

FIG. 1 is a schematic representation of the manner in which the present invention is utilized;

FIG. 2 is a sectional view of the device of the present invention illustrating the principal features thereof;

FIG. 3 is a fragmentary view of the device of FIG. 2 and illustrates the initial phase of operation of the ejection mechanism; and

FIG. 4 is a view similar to FIG. 2 representing the ejection sequence subsequent to that illustrated in FIG. 3 and showing the nose cap ejected and the chemical pellets beginning to deploy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 2 of the drawings, it can be seen that the simulator of the present invention comprises a substantially cylindrical charge holder or casing 10 having a tail fin assembly 11 fixed on one end thereof and having the other end closed by means of a nose cap 12 telescoped therein. The nose cap 12 is retained in this position by means of pins 14 fixed in the nose cap and disposed in corresponding apertures in the charge holder 10. The nose cap 12 is provided with an O-ring 15 to form a fluid tight seal with the charge holder 10.

A valve body 16 is disposed within the reduced portion of the charge holder to which the tail fin assembly 11 is secured. Disposed within the valve body 16 are a base 18, a retaining ring 19 for holding the base within the valve body, and a valve plug 20. The valve plug 20 is provided with an O-ring 21. which provides a fluid tight seal when in engagement with a tapered surface 22, formed in the interior of the valve body 16. A compression spring 24 is interposed between the base 18 and the valve plug 20 and normally urges the O-ring 21 into sealing engagement with the surface 22.

A plurality of water-reactive, gas-generating pellets 25 are disposed within the charge holder 10. These pellets may be made of lithium hydride or of various other substances, such as magnesium, which will react with water to produce a quantity of hydrogen or other gas. An elastomeric piston 26 is positioned within the carge holder between the stack of pellets 25 and the inner end of the valve body 16. The piston 26 is provided with a large-mesh, screen cover 28 which retains on the piston a number of water-reactive, gas generating tablets 29. These tablets 29 would normally be made of the same material as the pellets 25 although this need not be so.

OPERATION In order that a better understanding of the invention might be had, its mode of operation will now be described. Referring now to FIG. 1, there is depicted a ship 30 aboard which are the sonar operators to be trained. When all is in readiness, an aircraft 31 will drop a submarine target simulator into the water at a preselected distance from the ship 30. Alternatively, the simulator may be launched by hand from another ship or even a small boat. Due to the weight of the nose cap 12 and other metal parts, the target simulator will sink beneath the surface. At the desired operating depth, which is predetermined by the spring constant of the compression spring 24, the valve plug will b forced inwardly by water pressure opening the valve and admitting sea water into the interior of the charge holder 10 as shown in FIG. 3. The sea Water will penetrate the screen 28 and contact the tablets 29 which immediately begin reacting with the water and generating a large quantity of hydrogen gas. The hydrogen gas is generated so rapidly that the pressure exerted on the valve plug 20 by the gas, in conjunction with the force of the spring 24, exceeds the force on the valve plug 20 due to ambient water pressure and the valve closes.

Further reaction of the sea water with the tablets 29 results in a rapid increase in gas pressure within the charge holder 10 which applies an increasing force to the piston 26 which is in turn transmitted to the nose cap 12 through the pellets 25. The force continues to increase until the pins 14 shear through the thin sections of the charge older between the pins and the nose end of the charge holder permitting ejection of the nose cap 12 as shown in FIG. 4. The nose cap then sinks away and the compressed gas acting on the piston 26 rapidly ejects the pellets to deploy them in approximately the pattern shown in FIG. 1. The pellets 25 immediately begin reacting with the ambient water to generate a bubble stream 32. A sonar signal 34 from the ship will then produce a strong echo 35 which will be picked up by the sonar receiving equipment and will simulate the type of echo received from signals reflected off an actual submarine.

It is to be understood that numerous modifications will be readily apparent to those skilled in the art which will achieve similar devices still embodying the principles of the present invention and falling within the spirit and scope thereof.

What is claimed is:

1. An underwater submarine target simulator comprising:

a fluid tight casing;

a quantity of water-reactive, gas producing chemical material disposed in said casing;

means responsive to the water pressure at a predetermined depth for admitting water into one end of said casing; and

means responsive to admission of water for ejecting said chemical material from the other end of said casing whereby a bubble stream is generated simulating a submarine target.

2. An underwater submarine target simulator as defined in claim 1 wherein said admitting means comprises:

a normally closed valve; and

sequentially operable means responsive to admission of water for reclosing said valve and ejecting said chemical material.

3. An underwater submarine target simulator as defined in claim 2 wherein said sequentially operable means comprises:

a plurality of tablets of a water-reactive, gas-generating chemical material; and

means separating said tablets from said quantity of chemical material in gas sealing relationship with the walls of said casing.

4. An underwater submarine target simulator as defined in claim 3 wherein said separating means comprises:

an elastomeric piston slidable within said casing; and

means for carrying said tablets on said piston.

5. An underwater submarine target simulator as defined in claim 2 wherein said other end of said casing comprises:

a nose cap disposed in and connected to said other end of said casing; and

fluid sealing means interposed between said nose cap and said other end of said casing.

6. An underwater submarine target simulator as defined in claim 4 wherein said quantity of chemical material is selected from the group consisting of lithium hydride and magnesium.

7. An underwater submarine target simulator as defined in claim 6 wherein said tablets are made of a chemical material selected from the group consisting of lithium hydride and magnesium.

References Cited UNITED STATES PATENTS 6/1969 Buck et a1. 181-05 7/1963 Amundson et al.

OTHER REFERENCES RICHARD A. FARLEY, Primary Examiner U.S. c1. X.R. 340-5 

